1. Field of the Invention
The present invention relates to drive axle assemblies, and more particularly, to a drive axle assembly with structure designed to improve drive axle lubrication.
2. Discussion of Related Art
Most vehicles include one or more drive axle assemblies. A conventional drive axle assembly includes a pair of axle half shafts extending from a housing on which one or more wheels of a vehicle are mounted. The axle half shafts in the drive axle assembly are driven by a wheel differential disposed within the housing. The wheel differential includes a pinion gear in mesh with a ring gear (which in turn drives a plurality of bevel gears to cause rotation of the axle half shafts).
The drive axle assembly housing commonly has a front opening to allow for connection of an input shaft with an exterior yoke or flange which is in turn connected with a drive shaft of the vehicle. The input shaft powers the pinion gear of the wheel differential.
The drive axle assembly housing also commonly has a rear opening which is closed by a cover plate. The cover plate and drive axle assembly housing provide a lubricant sump or reservoir. The cover plate includes a relatively small opening through which lubricant is inserted into the drive axle assembly and into the sump. A plug is provided to close the opening.
In a conventional drive axle assembly, the ring gear picks up lubricant from the sump and causes lubricant movement so that lubricant is circulated within the drive axle assembly to lubricate the moving parts of the drive axle assembly. Conventional drive axle assemblies may contain deflectors to direct the lubricant or control lubricant levels. Conventional assemblies also may include filters to remove contaminants from the lubricant.
Conventional drive axle assemblies have several drawbacks. Conventional assemblies require the ring gear to churn through a relatively large amount of lubricant in the drive axle assembly. This churning has a negative impact on efficiency and fuel economy and also increases the temperature of the lubricant. One option for reducing churning losses is to reduce the lubricant level within the drive axle assembly. Doing so, however, reduces the useful life of the lubricant thereby increasing required maintenance (including more frequent draining and refilling of lubricant). Conventional drive axle assemblies also frequently suffer from the introduction of contaminants into the lubricant. Foundry sand may be present due to insufficient cleaning of the housing before the axle assembly operation. Further, operation of the assembly can cause particles of metal to be introduced into the lubricant. One option for addressing contamination is to use a filtration system to remove various contaminants present in the lubricant sump. Conventional filtration systems, however, typically require drainage of the lubricant to service the filtration system.
The inventors herein have recognized a need for a drive axle assembly that will minimize and/or eliminate the above-identified deficiencies.